User interfaces utilizing capacitive sensing include circuitry for detecting a capacitance change when a finger or other object is adjacent to a touch screen, touch pad, series of touch buttons, or other touch panel. The FIG. 1 shows an example electrode grid array 1 (also known as an electrode matrix) used by a touch sense device having a touch pad.
The array 1 includes rows 3 and columns 4 of electrodes overlaid by a dielectric (not shown). A charge is applied to both of the electrodes 3 and 4 by circuits 5 such that, if a finger or other conductive object is placed on the touch panel, the finger or other object increases capacitive coupling to ground.
The change in capacitance caused by the finger touching the touch panel can be detected by circuits 5 coupled to the electrodes 3 and 4. Ones of the circuits 5 that correspond to ones of the electrodes 3 and 4 that are closest to the finger measure different capacitance than the remaining circuits 5. These capacitive measurements can be used to identify which intersection of the electrodes 3 and the column electrodes 4 is closest to the finger, which can be used to pinpoint the position of the finger. This process is dynamic as the finger changes positions on the touch panel allowing the touch sense device to, for example, move a mouse pointer on a display to correspond with the finger movement.
The circuits 5 do not have the ability to resolve multiple presses, i.e. more than position on the touch panel are being touched simultaneously, or nearly simultaneously. The disclosure that follows solves this and other problems.